Bug in Mono on certain Android devices with IEnumerable

Suddenly, after moving to Unity 4.5 our app started to crash violently on galaxy s4 and other top devices on android. Investigation showed that crash was the result of wrong iterator type in our json library (json.fx). Quick googling showed that this error is present and active. Further investigation showed that after some unknown trigger-event following casts returned wrong type:

var x = new Dictionatry<string, object>();
((IEnumerable)((IDictionary)x)) -> KeyCollection

First cast to IDictionary results in ShimEnumerator which to my understaning is some mono hack to intertwine generic and non-generic dictionaries. Casting ShimEnumerator to IEnumerable produces KeyCollection, not Dictionary enumerator and it doesn't implement IDictionaryEnumerator.

All we did is just removed cast to IEnumerable (we don't use non-generic types in serialization) and it works as expected.

Hope that helps and will raise some flags to mono integration team.

PS: All other implementations of json parsers/writers start to crash as well, it's not json.fx specific error. Not that it's json specific error as well, we just don't have any other reflection-based code except this libraries.

 

Be worth submitting this as a bug report.

 

I will, but i can't reproduce it outside of our project, which i can't attach due to obvious reasons.

 

I posted bug report.

I want to also note that Android is never crashed from our mono errors until now, all errors was handled by unity game loop somewhere and stacktrace in console was all that happened. But trying to do foreach on resulting itterator CRASHES the game.

 

My JSON .NET port does not suffer from this issue and doesn't have any issues with generic collections on Android that I've been made aware of.